The invention relates generally to power electronics and more particularly to health monitoring of power electronics.
Power electronics including gate drivers and power electronic devices such as transistors, thyristors, and gate turn off thyristors, for example, are used in electronic systems such as inverters, rectifiers, and other converters, for example. Sudden failures of power electronics often occur without warning (that is, without an obvious degradation of device or system performance). Failures in gate drivers and power electronic devices can be particularly troublesome for power electronic equipment operating in critical systems, such as, for example, transportation systems (locomotives, aircraft, automotive), communication systems, utility systems, medical systems, data processing, manufacturing, and industrial systems.
Conventional diagnostic techniques for monitoring power electronic devices use highly invasive and/or destructive testing to determine the condition of a power electronic device. For two examples of such conventional techniques, see Hatle, M., Vobecky, J., xe2x80x9cAdvanced methods for diagnostics of the GTO thyristorxe2x80x9d, Microelectronics Journal, January 1993, vol. 24, no. 1-2, p. 147-155, and Dawson, F. P., Ruda, H., xe2x80x9cThermal Diagnostics of High Power Electrical and Optical Device Time to Failurexe2x80x9d, Conf. Proceedings. IEEE IAS Annual Meeting, 1993, p. 1248-1255. The methods described are unsuitable for testing power electronic devices while the power electronic devices are being used in a converter.
It would therefore be desirable to have a less invasive method and apparatus for determining the condition of the power electronic elements even when the power electronic devices are being used in a converter. Such a diagnostic measurement can be used to gauge the degradation of the power electronics over time for the purposes of failure prediction. In addition such diagnostic measurements can be used to determine the condition of ancillary systems such as, for example, cooling systems.
Briefly, according to one embodiment of the present invention, a method for monitoring the health of power electronics includes: providing a switch command to a power electronic device through a gate driver; measuring a switching time of the power electronic device; and using the switching time to determine a diagnostic condition of the power electronic device or the gate driver.